A processing system network, such as a computer network, is a combination of two or more independent nodes capable of communicating with one another over a communications path or link. A network node may be an independent processing system, such as a personal computer, or another processing system network.
Network nodes communicate with one another in order to share resources, such as databases and data files, software applications, hardware peripherals and communication links. Communication links are shared, for example, to enable two or more nodes which are not directly linked together to communicate through one or more intermediate nodes. Resource sharing generally involves the transfer and reception of large amounts of data. The data is typically divided into packets, frames, groups, etc. ("data packets"). Each data packet includes a collection of related data items, as well as any information necessary to route the data packet between network nodes.
Networks traditionally belong in one of two general categories, namely, local area networks ("LANs") and wide area networks ("WANs"). A LAN is a group of communicating nodes which are located relatively close to one another, such as within the same building or building complex. The communication links between LAN nodes are typically characterized by relatively high-speed data packet transfers. A WAN, on the other hand, is a collection of independent and distinct network nodes which work together over relatively long distances. Communication links between WAN nodes are routinely provided by third-party carriers such as by long-distance telephone companies. The InterNet is an example of a worldwide WAN. Communications between WAN nodes are generally characterized by relatively slower data packet transfers as compared with communications between LAN nodes.
Many organizations setup LANs at different strategic locations, such as on each floor of an office building or at each one of several different buildings. It often becomes necessary to share resources among LANs.
There are two broad approaches for establishing LAN-to-LAN communications, namely, private ownership and leasing from commercial communication suppliers. Many organizations setup their own private electric, microwave, light beam and/or fiber optic transmission systems to carry data locally around metropolitan areas and campuses. However, when communication connections extend beyond a particular area, circuits are typically leased from commercial suppliers, including telephone carriers such as AT&T (New York, N.Y.) and MCI (Washington, D.C.); specialized communications companies such as Tymnet (British Telecommunications Public Limited Company, located in London, England) and Telenet (Sprint International Communication Corporation, located in Reston, Va.); and satellite system providers such as GTE (Stamford, Conn.).
Leased services typically fall into one of three general categories, namely, circuit-switched, full-period and packet-switched. Circuit-switched services are those with a dial tone, such as switched-56 digital services or the Integrated Services Digital Network ("ISDN"), for example, wherein a connection is dialed, data is transferred, and the system hangs up upon completion of the transaction. Full-period services, such as leased telephone lines, provide a circuit dedicated to an organization's full time use. Packet-switched systems, such as CompuServe (Columbus, Ohio), Tymnet and SprintNet (Kansas City, Mo.), for example, allow multi-point connections for bursts of short data packets. Packet-switched networks, also called X.25 networks after an older Consultive Committee International Telegraph and Telephone ("CCITT") packet-switching standard, commonly use a newer standard called frame relay.
Network portal devices are used to couple LANs and WANs together (i.e., LAN-to-LAN, LAN-to-WAN and WAN-to-WAN). The conventional approach is to use the portal device as a junction point through which data packets received from a source network are routed to one or more destination networks. The portal device typically includes control circuitry and a memory.
The memory typically includes the routing address for each LAN and each WAN coupled to the portal device, and typically includes the address of one or more of the nodes of each of the LANs and WANs. In the event that a particular network node is itself a LAN or a WAN, the addresses of one or more of its nodes are also often stored within the memory.
When a data packet is forwarded from a LAN node to a WAN node, the data packet is received by the portal device. The control circuitry searches the memory and retrieves the address of the destination WAN node. The control circuitry recognizes from the memory search that the destination node exists on a WAN and will typically wrap the data packet in a "data envelope" along with additional routing and transmission information. This additional information tells the commercial communication suppler how to route the data packet to the destination WAN node.
In an alternative case wherein a data packet is forwarded from one LAN node to another LAN node, the data packet is received by the portal device and the control circuitry is again required to search the memory. The control circuitry upon retrieving the address of the destination LAN node from memory determines whether the data packet requires additional processing, such as being wrapped in the aforementioned data envelope. Upon a determination that no additional processing is required, the control circuitry forwards the data packet to the destination LAN node.
Thus, although the foregoing process is both necessary and effective for processing a data packet routed to the WAN, it is equally unnecessary and ineffective when routing a data packet between LAN nodes. In point of fact the search and retrieval processes performed by the control circuitry when transferring a data packet from one locally connected LAN to another cause significant delays. The delay is compounded by the determination as to whether the data packet requires additional processing. These delays are compounded still further when considering that the portal device may, and often does, receive hundreds, if not thousands, of data packets per second. Many, if not most, of these data packets are queued and routed on a first come, first serve basis. A LAN-to-LAN data packet that is preceded by several data packets requiring special processing typically is required to wait unnecessarily. This wait curtails portal device throughput and the overall functionality of the processing system network.
Accordingly, there exists a need in the art to substantially eliminate delays associated with routing a data packet between two nodes wherein the data packet requires little or no additional processing.
There exists a further need to substantially eliminate delays associated with routing a data packet from a source LAN to a destination LAN.
There exists a still further need to reduce over-all memory access time associated with searching and retrieving addressing data from the memory of a portal device.